The concept of software architecture has created a new scenario for incorporating non-functional and transactional requirements into the software design. Transactional and non-functional requirements can be included in an architecture-based software development through formal approaches in which first-order and temporal logic are utilised to deal with them. In this paper, we present an approach in which transactional and non-functional requirements are formally incorporated into a special class of software architectures, known as dynamic software architectures. In order to demonstrate how this proposal can be utilised in a real application, an appointment system is presented.